This invention relates to a tamper-proof screw type container closure and more particularly to a thermoplastic synthetic plastic tamper-proof screw type container closure having an internal projection which normally precludes rotation of the closure on the container, and an integral tear tab which can be swung radially outwardly and upwardly to move the locking projection to an unlocked position permitting removal of the closure.
Container closures with liners have been provided heretofore to seal the lip of the container and prevent leakage of the container contents. Such liners sometimes comprise a disc of sealing material which is secured to the closure topwall by adhesive. The manufacture of such devices includes an extra step in the manufacturing process.
Another container closure is disclosed in the U.S. Pat. No. 3,866,845 granted to Frederick D. Keeler on Feb. 18, 1975. The Keeler Patent discloses a container closure made from a sandwich of two different materials which are bonded together and then molded to the required cap shape. External threads are formed on the sidewall or skirt of the container closure disclosed in the Keeler et al Patent. In the Keeler et al device, the finished product includes a liner which is bonded to the outer shell of the closure throughout the entire inner surface of the container.
Accordingly, it is an object of the present invention to provide a container closure having an outer shell and an inner foam liner which are concurrently molded to the shape of the closure but without sealing the foam liner to the entire inner surface of the endwall of the closure.
It is another object of the present invention to provide a method of making a container closure wherein superposed sheets of different materials are deformed to form a closure with internal threads bonded along only a portion thereof.
The Keeler et al patent discloses a container closure having an external thread. Container capper machines utilized to cap bottles generally have expansible and contractible jaws which must grip the outside of the container cap as the cap is being applied to the bottle. Some of the prior caps have a generally smooth outer sidewall surface and thus some of the capper machines incorporate rubber jaws which grip the outside of the container cap to minimize slippage of the jaws and the cap during the capping operation. The walls of the caps are generally quite thin, and the clamping pressure of the rubber jaws sometimes deforms the caps and thus causes problems during the capping operation.
Another prior art cap construction has incorporated circumferentially spaced serrations in the sidewall of the cap above the uppermost external thread. Attempts have been made to substitute metal jaws for the rubber clamping jaws. This construction is sometimes unsatisfactory because the gripping area is insufficient. Accordingly, it is another object of the present invention to provide a container closure having an increased capper gripping surface.
Still another object of the present invention to provide a container closure of the type described having a sidewall provided with internal threads and corrugations axially above and below the threads to enhance gripping by the capping jaws.
Container closures have been formed with internal threads heretofore, but such closure threads are formed by merely increasing the thickness of the sidewall at the thread portion of the cap. Such a construction has the disadvantage of utilizing substantially increased material. Accordingly, yet another object of the invention is to provide an internally threaded container closure of the type described having a sidewall which is substantially uniform in radial thickness.
A tamper-proof closure is disclosed in the U.S. Pat. No. 3,980,195 issued to William E. Fillmore on Sept. 14, 1976. This patent discloses a split, tamper-proof ring which is connected to the main closure body by a severable connection. This patent also discloses a severable bridge, which extends between the opposed free ends of the ring. The ring has a plurality of internal projections which lock with projection around the container to prevent turning of the ring. When the ring is broken, the resulting free end of the ring is used as a pull tab, to break the severable connection between the closure body and the tamper-proof ring. Housewives frequently encounter substantial difficulty in severing the bridge which is time consuming and irritating to the consumer. Moreover, when the ring is severed, the ring is subject to being inadvertently deposited into, and contaminating, the container contents.
Accordingly, a further object of the present invention to provide a tamper-proof closure having an internal projection which mates with external projections on the container to prevent turning of the closure and which is movable with a radially outwardly swingable break-away tab to a removed position, so that the closure can be turned.
Another object of the present invention is to provide a tamper-proof container closure including a locking projection which can be moved to an unlocked position, and which remains integral with the closure after it is moved to the unlocked position.
A still further object of the present invention is to provide a tamper-proof bottle cap of the type described including a sidewall integrally mounting a tear facilitating tab including a radially inwardly projecting locking projection.
It is another object of the present invention to provide a tamper-proof bottle cap of the type described including tear facilitating portions on opposite sides of a tear-away tab to permit the tab to be swung radially outwardly and axially to a removed position in which the locking projection can be removed from the container.
Yet another object of the present invention is to provide a tamper-proof container closure of the type described including a sidewall having a substantially uniform radial thickness and having an internal thread formed therein, and a plurality of circumferentially disposed, longitudinal corrugations, on longitudinally opposite sides of the screw thread.
Still another object of the present invention is to provide a tamper-proof closure for a milk container and the like including a cup shaped shell and a complementary inner foam liner which is not bonded to the central portion of the shell endwall.
One of the prior art constructions relies on sufficient torque being applied to the cap to deform the sealing liner against the sealing lip of the container. Such cap constructions require relatively heavy threads. The U.S. Pat. No. 3,980,195 granted to Fillmore discloses an internal, annular sealing ring which bears against the inner surface of the container neck. Such a construction complicates the manufacturing process and requires additional cap material to effect sealing.
The cap constructed according to the present invention has a deformable endwall and a sidewall which is normally spaced from the sidewall of the container neck adjacent the threads. As the cap is turned onto the container, the upper wall of the cap will bear against the sealing lip and will yieldably bow outwardly as the cap is threaded onto the container. Shortly after the cap starts to bow, the sidewall of the cap will "bottom out" against the shoulder of the bottle to further seal the cap to the container.
Accordingly, it is another object of the present invention to provide a container closure which will permit a wider range of torque applied by the cappers during the sealing process.
It is another object of the present invention to provide a closure having an endwall which will seal to the lip of the container and an annular sidewall having a lower terminal edge portion which will thereafter abut and seal to a shoulder portion of the container.
Another object of the present invention is to provide a closure cap of the type described including an integral tear tab which lies in a plane parallel to the plane of the terminal edge of the sidewall and including tear facilitating notches on circumferentially opposite sides of the tab to permit the sidewall of the closure to tear and permit the tab to be swung radially outwardly and upwardly to a removed position.
These and other objects of the present invention will become more readily apparent as the description thereof proceeds.